Since the invention of lasers, optics made of glass, quartz, zinc selenide, germanium and numerous other focusing mediums shaped into the form of lenses have been used to concentrate the raw, unfocused laser beam onto targets of many types. Anti-reflective coatings have been developed and applied to the expensive optics to permit transmission of the laser beam through the lens medium. However, at extremely high powers, the unfocused laser beam rapidly degenerates the lens material.
A significant problem that occurs during the use of high-powered laser systems is the distortion of the laser beam and/or damage to the lens material. Since many of the advanced lens optics can cost hundreds or even thousands of dollars, lens damage creates a significant problem. Further, the removal and replacement of a damaged lens can result in large amounts of time lost during the actual replacement procedure.
Since current lenses are made from light-transmitting materials, environmental factors can have a large effect on the functionality of the lens. For example, humidity can create damage to the lens optics due to the condensation of water on the lens surface. Further, use of lens optics in warm environments requires the use of cooling systems.
In some applications of lasers including lenses made from light-transmitting materials, the laser is used in a harsh operating environment, such as a desert. In this type of operating environment, small particles of sand or other debris can scratch or damage the optics, thereby limiting the use of such devices.
In addition to the use of optics, alternate focusing devices include the use of mirrored focusing technology. Although mirrored focusing technology addresses some of the problems created by the currently available optics, mirrored focusing devices do not provide the required performance of costly optics.
Therefore, a need clearly exists for technology to replace both optical focusing materials for lenses and mirrored focusing technology. The use of such improved technology would allow focusing devices to be used in many different operating environments, such as space where optics can be easily degraded by cosmic radiation and solar wind. Therefore, it is an object of the present invention to provide a laser focusing device that does not utilize lens optics. Further, it is an object of the present invention to provide a focusing device that provides the required focusing while being able to be used in a harsh operating environment. A still further object of the present invention is to provide a focusing device that can be manufactured at a relatively low cost and easily replaced upon damage.
The present invention is a lensless focusing device for focusing an input, raw laser beam to create an output pattern of laser profiles. The focusing device of the present invention eliminates expensive and fragile optics while focusing an input laser beam into a usable output pattern.
The focusing device of the present invention includes a pair of wedge plate formed from a metallic material, such as aluminum, stainless steel or other reflective materials. Each of the wedge plates extends from an inlet end to a discharge end and includes a generally planar face surface that extends from the inlet end to the discharge end. The face surface of each wedge plate is a highly polished surface that reflects a laser beam upon contact of the laser beam on the polished surface.
The focusing device is formed from the pair of wedge plates each positioned at a reflection angle relative to the projection axis of the input laser beam. The wedge plate are positioned on opposite sides of the projection axis and each diverge from the projection axis at the reflection angle.
The focusing device includes an inlet opening that is defined by the distance between the inlet ends of the pair of wedge plates. The inlet opening has a width that is greater than the width of the input laser beam such that the inlet opening receives the entire input laser beam. Preferably, the pair of wedge plates are secured to each other to accurately define the width of the inlet opening.
Since the pair of wedge plates are oriented at an angle relative to the projection axis of the input laser beam, the wedge plates define a discharge opening having a width less than the width of the inlet opening. Further, the size of the wedge plates and the reflection angle insures that the width of the discharge opening is less than the width of the input laser beam such that the input laser beam is reflected off of the pair of face surfaces of the wedge plate toward the discharge opening.
As the individual light beams of the input laser beam are reflected toward the discharge opening, the focusing device creates an output pattern of individual laser profiles. In one embodiment of the invention, the output pattern includes a plurality of spaced laser profiles that each take the form of an elongated laser line. The individual laser profiles are spaced from each other to define the output pattern.
The output pattern from the single focusing device includes a plurality of fixed laser profiles and a plurality of adjustable laser profiles. The adjustable laser profiles are each positioned between two of the fixed laser profiles. When the focusing device is rotated about the projection axis, the adjustable laser profiles move in either direction relative to the fixed laser profiles. For example, if the focusing device is rotated in a counter-clockwise direction, the adjustable laser profiles move left when viewed from above. Likewise, if the focusing device is rotated in a clockwise direction, the adjustable laser profiles move to the right. By rotating the focusing device, the distance between the adjustable and fixed laser profiles can be adjusted to create a unique output pattern.
The lensless focusing device of the invention utilizes a pair of solid wedge plates to create an output pattern having multiple laser profiles. The multiple laser profiles can be used in many applications, such as isotope separation in a nuclear material.
In a second embodiment of the invention, a pair of focusing devices are positioned in series along the projection axis of the input laser beam. The first focusing device receives the input laser beam and generates the output pattern having a series of spaced laser profiles. The output pattern from the first focusing device is then received within the inlet opening for the second focusing device. The second focusing device is rotated 90xc2x0 relative to the first focusing device such that the entire first output pattern is received within the inlet opening of the second focusing device.
The multiple, spaced laser profiles from the first focusing device fall onto the face surfaces of the second focusing device and create a second output pattern from the discharge end of the second focusing device. In the embodiment of the invention discussed, the second output pattern has a grid shape in which multiple points on the grid are adjustable, while other points on the grid are fixed. The movement of the adjustable grid profiles can be controlled by rotating either the first focusing device or the second focusing device along the projection axis of the input laser beam.
Various other features, objects and advantages of the invention will be made apparent from the following description taken together with the drawings.